Imbalanced Earth? Tug of Sun, Moon Drives Planet's Plate Motion

A new study shows that the Earth-moon-sun system's uneven stresses and torques drive mantle circulation.

According to scientists at Washington University in St. Louis, large things are moved by force, not heat. The moon's orbits around Earth grow prolonged due to the sun's tremendous gravitational attraction.

Their study, "Links of Planetary Energetics to Moon Size, Orbit, and Planet Spin: A New Mechanism for Plate Tectonics," was published in the Geological Society of America.

Research Shows San Andreas Fault May Be Overdue For Large Earthquake

(Photo: David McNew/Getty Images)
CALIPATRIA, CA - JUNE 30: Small mud volcanoes grow above the southern San Andreas Fault near the Salton Sea on June 30 near Calipatria, California. Scientists have discovered that human-created changes affecting the Salton Sea appear to be why California's massive "Big One" earthquake is more than 100 years overdue and is building up for the greatest disaster ever to hit Los Angeles and Southern California. Researchers found that the San Andreas Fault strands under the 45-mile long rift lake have generated at least five 7.0 or larger quakes about every 180 years. This ended in the early 20th century when authorities stopped massive amounts of Colorado River water from periodically flooding into this sub-sea level desert basin. Such floods regularly trigger major quakes and relieve building seismic pressure, but the last big earthquake on the southern San Andreas was about 325 years ago. Dangerous new fault branches that could trigger a 7.8 quake have recently been discovered under the Salton Sea.

Earth's Tectonic Plates Moving Due to Sun's Attraction to Moon

Phys.org said the inside workings of the Earth are commonly depicted as dispersing heat generated by internal radioactivity and residual energy released during our planet's formation events.

Even proponents of mantle convection acknowledge that the quantity of internal heat energy required to drive large-scale tectonics is inadequate. Furthermore, employing convection to explain observed plate movements has significant drawbacks.

Instead, Earth's plates may be moving due to the sun's gravitational solid attraction on the moon, which has led the moon's orbit around Earth to lengthen.

ALSO READ: Earth Is Cooling Faster Than Expected; Thermal Conductivity Measured in Between Mantle and Core

According to Hofmeister, the barycenter-the center of mass between the Earth and the moon's orbital bodies-has migrated closer to the Earth's surface through time and presently oscillates 600 kilometers every month relative to the geocenter. As the Earth continues to rotate, internal tensions are created.

Earth's tangential orbital acceleration and solar attraction are unbalanced except at the barycenter because the oscillating barycenter is 4600 km from the geocenter, Hofmeister explained. He added that the planet's warm, thick, and strong core layers could endure these forces, while the lithosphere's thin, cold, and fragile outside layers fracture.

Volcanism, Tectonism Depend on Moon Size, Distance to Sun

The Earth's daily rotation flattens it from a perfectly spherical form, contributing to the lithosphere's brittle breakdown. According to scientists, these two distinct pressures are responsible for the mosaic of plates seen in the outer shell. Plate movements vary due to variations in the amount and direction of uneven gravitational forces throughout time.

Hofmeister said per Tech Explorist that a careful analysis of the tectonics of Pluto, which is too tiny and frigid to convect yet has a large moon and a remarkably youthful surface,"

The study contains a comparison of rocky planets that demonstrates that the occurrence and persistence of volcanism and tectonism are dependent on a unique combination of moon size, orbital orientation, closeness to the sun, and body spin and cooling rates.

According to Hofmeister, Earth is the only rocky planet with all the necessary ingredients for plate tectonics.